Cоздать в памяти архив, а затем отправить его через Webhook

Я делаю отправку архива через Discord Webhook, не создавая его на диске (Полностью в памяти). Пытался использовать стандартный System.IO Zip, но там нет нормального сохранения в Stream, поэтому использую IonicZip, т.к его использовал раньше для создания архивов на диске. Вот мой код:

Stream stream = new MemoryStream();
Stream myFile = new MemoryStream();
StreamWriter myFileStream = new StreamWriter(myFile, Encoding.UTF8);
ZipFile archive = new ZipFile();
myFileStream.WriteLine("My data.");
archive.AddEntry("myFile.txt", myFile);
archive.Save(stream);
archive.Save("C:\\myFiles.zip");
DiscordWebhook.SendStream("qq", "qq.zip", stream);

Webhook:

        public static string SendStream(
            string mssgBody,
            string filename,
            Stream stream)
        {
            byte[] data = new byte[stream.Length];
            stream.Read(data, 0, data.Length);

            Dictionary<string, object> postParameters = new Dictionary<string, object>();
            postParameters.Add("filename", filename);
            postParameters.Add("fileformat", ".zip");
            postParameters.Add("file", new FormUpload.FileParameter(data, filename, ""/*"application/msexcel"*/));

            postParameters.Add("username", defaultUserName);
            postParameters.Add("content", mssgBody);

            HttpWebResponse webResponse = FormUpload.MultipartFormDataPost(defaultWebhook, defaultUserAgent, postParameters);

            StreamReader responseReader = new StreamReader(webResponse.GetResponseStream());
            string fullResponse = responseReader.ReadToEnd();
            webResponse.Close();

            return fullResponse;
        }
    public static class FormUpload //formats data as a multi part form to allow for file sharing
        {
            private static readonly Encoding encoding = Encoding.UTF8;
            public static HttpWebResponse MultipartFormDataPost(string postUrl, string userAgent, Dictionary<string, object> postParameters)
            {
                string formDataBoundary = String.Format("----------{0:N}", Guid.NewGuid());

                string contentType = "multipart/form-data; boundary=" + formDataBoundary;

                byte[] formData = GetMultipartFormData(postParameters, formDataBoundary);

                return PostForm(postUrl, userAgent, contentType, formData);
            }

            private static HttpWebResponse PostForm(string postUrl, string userAgent, string contentType, byte[] formData)
            {
                HttpWebRequest request = WebRequest.Create(postUrl) as HttpWebRequest;

                if (request == null)
                {
                    throw new NullReferenceException("request is not a http request");
                }

                // Set up the request properties.
                request.Method = "POST";
                request.ContentType = contentType;
                request.UserAgent = userAgent;
                request.CookieContainer = new CookieContainer();
                request.ContentLength = formData.Length;

                // Send the form data to the request.
                using (Stream requestStream = request.GetRequestStream())
                {
                    requestStream.Write(formData, 0, formData.Length);
                    requestStream.Close();
                }

                return request.GetResponse() as HttpWebResponse;
            }

            private static byte[] GetMultipartFormData(Dictionary<string, object> postParameters, string boundary)
            {
                Stream formDataStream = new System.IO.MemoryStream();
                bool needsCLRF = false;

                foreach (var param in postParameters)
                {
                    if (needsCLRF)
                        formDataStream.Write(encoding.GetBytes("\r\n"), 0, encoding.GetByteCount("\r\n"));

                    needsCLRF = true;

                    if (param.Value is FileParameter)
                    {
                        FileParameter fileToUpload = (FileParameter)param.Value;

                        string header = string.Format("--{0}\r\nContent-Disposition: form-data; name=\"{1}\"; filename=\"{2}\"\r\nContent-Type: {3}\r\n\r\n",
                            boundary,
                            param.Key,
                            fileToUpload.FileName ?? param.Key,
                            fileToUpload.ContentType ?? "application/octet-stream");

                        formDataStream.Write(encoding.GetBytes(header), 0, encoding.GetByteCount(header));

                        formDataStream.Write(fileToUpload.File, 0, fileToUpload.File.Length);
                    }
                    else
                    {
                        string postData = string.Format("--{0}\r\nContent-Disposition: form-data; name=\"{1}\"\r\n\r\n{2}",
                            boundary,
                            param.Key,
                            param.Value);
                        formDataStream.Write(encoding.GetBytes(postData), 0, encoding.GetByteCount(postData));
                    }
                }

                // Add the end of the request.  Start with a newline
                string footer = "\r\n--" + boundary + "--\r\n";
                formDataStream.Write(encoding.GetBytes(footer), 0, encoding.GetByteCount(footer));

                // Dump the Stream into a byte[]
                formDataStream.Position = 0;
                byte[] formData = new byte[formDataStream.Length];
                formDataStream.Read(formData, 0, formData.Length);
                formDataStream.Close();

                return formData;
            }

            public class FileParameter
            {
                public byte[] File { get; set; }
                public string FileName { get; set; }
                public string ContentType { get; set; }
                public FileParameter(byte[] file) : this(file, null) { }
                public FileParameter(byte[] file, string filename) : this(file, filename, null) { }
                public FileParameter(byte[] file, string filename, string contenttype)
                {
                    File = file;
                    FileName = filename;
                    ContentType = contenttype;
                }
            }

        }

При проходе этого кода я получаю:

Если открыть файл через txt, то все символы - пробелы